1. Field of the Invention:
This invention relates to a system for measuring displacement distance between two objects which move relative to each other and, in particular, to a high resolution opto-electronic system for measuring displacement distance with reference to a structure having a ruled scale. The high resolution of measurement is obtained by generating on the opto-electronic system eight pulses corresponding to the displacement for each division of the scale.
2. Brief Description of the Prior Art:
In the field of ultra precise measuring instrumentation, particularly for use with machine tools, transducer systems for measuring displacement of either the tool or the workpiece have long been the subject of attempts to increase measurement resolution and accuracy while controlling the cost to accomplish such results. The approaches to achieve improved results involve such things as reducing the wavelength of the cyclic pattern which is limited, for example, by the fineness of the physical rulings of the gratings. Some attempts have been made to provide unique ruling patterns on gratings which has made their manufacture more difficult and expensive. The incorporation of more detectors, to provide additional signal output information has added additional circuitry and increased the complexity of the electrical system necessary to process the signals.